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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper.server.persistence;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.nio.file.Files;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.jute.Record;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.KeeperException.Code;
import org.apache.zookeeper.ZooDefs.OpCode;
import org.apache.zookeeper.common.Time;
import org.apache.zookeeper.server.DataTree;
import org.apache.zookeeper.server.DataTree.ProcessTxnResult;
import org.apache.zookeeper.server.Request;
import org.apache.zookeeper.server.ServerMetrics;
import org.apache.zookeeper.server.ServerStats;
import org.apache.zookeeper.server.ZooTrace;
import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator;
import org.apache.zookeeper.txn.CreateSessionTxn;
import org.apache.zookeeper.txn.TxnDigest;
import org.apache.zookeeper.txn.TxnHeader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This is a helper class
* above the implementations
* of txnlog and snapshot
* classes
*/
public class FileTxnSnapLog {
//the directory containing the
//the transaction logs
final File dataDir;
//the directory containing the
//the snapshot directory
final File snapDir;
TxnLog txnLog;
SnapShot snapLog;
private final boolean autoCreateDB;
private final boolean trustEmptySnapshot;
public static final int VERSION = 2;
public static final String version = "version-";
private static final Logger LOG = LoggerFactory.getLogger(FileTxnSnapLog.class);
public static final String ZOOKEEPER_DATADIR_AUTOCREATE = "zookeeper.datadir.autocreate";
public static final String ZOOKEEPER_DATADIR_AUTOCREATE_DEFAULT = "true";
static final String ZOOKEEPER_DB_AUTOCREATE = "zookeeper.db.autocreate";
private static final String ZOOKEEPER_DB_AUTOCREATE_DEFAULT = "true";
public static final String ZOOKEEPER_SNAPSHOT_TRUST_EMPTY = "zookeeper.snapshot.trust.empty";
private static final String EMPTY_SNAPSHOT_WARNING = "No snapshot found, but there are log entries. ";
/**
* This listener helps
* the external apis calling
* restore to gather information
* while the data is being
* restored.
*/
public interface PlayBackListener {
void onTxnLoaded(TxnHeader hdr, Record rec, TxnDigest digest);
}
/**
* Finalizing restore of data tree through
* a set of operations (replaying transaction logs,
* calculating data tree digests, and so on.).
*/
private interface RestoreFinalizer {
/**
* @return the highest zxid of restored data tree.
*/
long run() throws IOException;
}
/**
* the constructor which takes the datadir and
* snapdir.
* @param dataDir the transaction directory
* @param snapDir the snapshot directory
*/
public FileTxnSnapLog(File dataDir, File snapDir) throws IOException {
LOG.debug("Opening datadir:{} snapDir:{}", dataDir, snapDir);
this.dataDir = new File(dataDir, version + VERSION);
this.snapDir = new File(snapDir, version + VERSION);
// by default create snap/log dirs, but otherwise complain instead
// See ZOOKEEPER-1161 for more details
boolean enableAutocreate = Boolean.parseBoolean(
System.getProperty(ZOOKEEPER_DATADIR_AUTOCREATE, ZOOKEEPER_DATADIR_AUTOCREATE_DEFAULT));
trustEmptySnapshot = Boolean.getBoolean(ZOOKEEPER_SNAPSHOT_TRUST_EMPTY);
LOG.info("{} : {}", ZOOKEEPER_SNAPSHOT_TRUST_EMPTY, trustEmptySnapshot);
if (!this.dataDir.exists()) {
if (!enableAutocreate) {
throw new DatadirException(String.format(
"Missing data directory %s, automatic data directory creation is disabled (%s is false)."
+ " Please create this directory manually.",
this.dataDir,
ZOOKEEPER_DATADIR_AUTOCREATE));
}
if (!this.dataDir.mkdirs() && !this.dataDir.exists()) {
throw new DatadirException("Unable to create data directory " + this.dataDir);
}
}
if (!this.dataDir.canWrite()) {
throw new DatadirException("Cannot write to data directory " + this.dataDir);
}
if (!this.snapDir.exists()) {
// by default create this directory, but otherwise complain instead
// See ZOOKEEPER-1161 for more details
if (!enableAutocreate) {
throw new DatadirException(String.format(
"Missing snap directory %s, automatic data directory creation is disabled (%s is false)."
+ "Please create this directory manually.",
this.snapDir,
ZOOKEEPER_DATADIR_AUTOCREATE));
}
if (!this.snapDir.mkdirs() && !this.snapDir.exists()) {
throw new DatadirException("Unable to create snap directory " + this.snapDir);
}
}
if (!this.snapDir.canWrite()) {
throw new DatadirException("Cannot write to snap directory " + this.snapDir);
}
// check content of transaction log and snapshot dirs if they are two different directories
// See ZOOKEEPER-2967 for more details
if (!this.dataDir.getPath().equals(this.snapDir.getPath())) {
checkLogDir();
checkSnapDir();
}
txnLog = new FileTxnLog(this.dataDir);
snapLog = new FileSnap(this.snapDir);
autoCreateDB = Boolean.parseBoolean(
System.getProperty(ZOOKEEPER_DB_AUTOCREATE, ZOOKEEPER_DB_AUTOCREATE_DEFAULT));
}
public void setServerStats(ServerStats serverStats) {
txnLog.setServerStats(serverStats);
}
private void checkLogDir() throws LogDirContentCheckException {
File[] files = this.dataDir.listFiles(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return Util.isSnapshotFileName(name);
}
});
if (files != null && files.length > 0) {
throw new LogDirContentCheckException(
"Log directory has snapshot files. Check if dataLogDir and dataDir configuration is correct.");
}
}
private void checkSnapDir() throws SnapDirContentCheckException {
File[] files = this.snapDir.listFiles(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return Util.isLogFileName(name);
}
});
if (files != null && files.length > 0) {
throw new SnapDirContentCheckException(
"Snapshot directory has log files. Check if dataLogDir and dataDir configuration is correct.");
}
}
/**
* get the datadir used by this filetxn
* snap log
* @return the data dir
*/
public File getDataDir() {
return this.dataDir;
}
/**
* get the snap dir used by this
* filetxn snap log
* @return the snap dir
*/
public File getSnapDir() {
return this.snapDir;
}
/**
* get information of the last saved/restored snapshot
* @return info of last snapshot
*/
public SnapshotInfo getLastSnapshotInfo() {
return this.snapLog.getLastSnapshotInfo();
}
/**
* this function restores the server
* database after reading from the
* snapshots and transaction logs
* @param dt the datatree to be restored
* @param sessions the sessions to be restored
* @param listener the playback listener to run on the
* database restoration
* @return the highest zxid restored
* @throws IOException
*/
public long restore(DataTree dt, Map sessions, PlayBackListener listener) throws IOException {
long snapLoadingStartTime = Time.currentElapsedTime();
long deserializeResult = snapLog.deserialize(dt, sessions);
ServerMetrics.getMetrics().STARTUP_SNAP_LOAD_TIME.add(Time.currentElapsedTime() - snapLoadingStartTime);
FileTxnLog txnLog = new FileTxnLog(dataDir);
boolean trustEmptyDB;
File initFile = new File(dataDir.getParent(), "initialize");
if (Files.deleteIfExists(initFile.toPath())) {
LOG.info("Initialize file found, an empty database will not block voting participation");
trustEmptyDB = true;
} else {
trustEmptyDB = autoCreateDB;
}
RestoreFinalizer finalizer = () -> {
long highestZxid = fastForwardFromEdits(dt, sessions, listener);
// The snapshotZxidDigest will reset after replaying the txn of the
// zxid in the snapshotZxidDigest, if it's not reset to null after
// restoring, it means either there are not enough txns to cover that
// zxid or that txn is missing
DataTree.ZxidDigest snapshotZxidDigest = dt.getDigestFromLoadedSnapshot();
if (snapshotZxidDigest != null) {
LOG.warn(
"Highest txn zxid 0x{} is not covering the snapshot digest zxid 0x{}, "
+ "which might lead to inconsistent state",
Long.toHexString(highestZxid),
Long.toHexString(snapshotZxidDigest.getZxid()));
}
return highestZxid;
};
if (-1L == deserializeResult) {
/* this means that we couldn't find any snapshot, so we need to
* initialize an empty database (reported in ZOOKEEPER-2325) */
if (txnLog.getLastLoggedZxid() != -1) {
// ZOOKEEPER-3056: provides an escape hatch for users upgrading
// from old versions of zookeeper (3.4.x, pre 3.5.3).
if (!trustEmptySnapshot) {
throw new IOException(EMPTY_SNAPSHOT_WARNING + "Something is broken!");
} else {
LOG.warn("{}This should only be allowed during upgrading.", EMPTY_SNAPSHOT_WARNING);
return finalizer.run();
}
}
if (trustEmptyDB) {
/* TODO: (br33d) we should either put a ConcurrentHashMap on restore()
* or use Map on save() */
save(dt, (ConcurrentHashMap) sessions, false);
/* return a zxid of 0, since we know the database is empty */
return 0L;
} else {
/* return a zxid of -1, since we are possibly missing data */
LOG.warn("Unexpected empty data tree, setting zxid to -1");
dt.lastProcessedZxid = -1L;
return -1L;
}
}
return finalizer.run();
}
/**
* This function will fast forward the server database to have the latest
* transactions in it. This is the same as restore, but only reads from
* the transaction logs and not restores from a snapshot.
* @param dt the datatree to write transactions to.
* @param sessions the sessions to be restored.
* @param listener the playback listener to run on the
* database transactions.
* @return the highest zxid restored.
* @throws IOException
*/
public long fastForwardFromEdits(
DataTree dt,
Map sessions,
PlayBackListener listener) throws IOException {
TxnIterator itr = txnLog.read(dt.lastProcessedZxid + 1);
long highestZxid = dt.lastProcessedZxid;
TxnHeader hdr;
int txnLoaded = 0;
long startTime = Time.currentElapsedTime();
try {
while (true) {
// iterator points to
// the first valid txn when initialized
hdr = itr.getHeader();
if (hdr == null) {
//empty logs
return dt.lastProcessedZxid;
}
if (hdr.getZxid() < highestZxid && highestZxid != 0) {
LOG.error("{}(highestZxid) > {}(next log) for type {}", highestZxid, hdr.getZxid(), hdr.getType());
} else {
highestZxid = hdr.getZxid();
}
try {
processTransaction(hdr, dt, sessions, itr.getTxn());
dt.compareDigest(hdr, itr.getTxn(), itr.getDigest());
txnLoaded++;
} catch (KeeperException.NoNodeException e) {
throw new IOException("Failed to process transaction type: "
+ hdr.getType()
+ " error: "
+ e.getMessage(),
e);
}
listener.onTxnLoaded(hdr, itr.getTxn(), itr.getDigest());
if (!itr.next()) {
break;
}
}
} finally {
if (itr != null) {
itr.close();
}
}
long loadTime = Time.currentElapsedTime() - startTime;
LOG.info("{} txns loaded in {} ms", txnLoaded, loadTime);
ServerMetrics.getMetrics().STARTUP_TXNS_LOADED.add(txnLoaded);
ServerMetrics.getMetrics().STARTUP_TXNS_LOAD_TIME.add(loadTime);
return highestZxid;
}
/**
* Get TxnIterator for iterating through txnlog starting at a given zxid
*
* @param zxid starting zxid
* @return TxnIterator
* @throws IOException
*/
public TxnIterator readTxnLog(long zxid) throws IOException {
return readTxnLog(zxid, true);
}
/**
* Get TxnIterator for iterating through txnlog starting at a given zxid
*
* @param zxid starting zxid
* @param fastForward true if the iterator should be fast forwarded to point
* to the txn of a given zxid, else the iterator will point to the
* starting txn of a txnlog that may contain txn of a given zxid
* @return TxnIterator
* @throws IOException
*/
public TxnIterator readTxnLog(long zxid, boolean fastForward) throws IOException {
FileTxnLog txnLog = new FileTxnLog(dataDir);
return txnLog.read(zxid, fastForward);
}
/**
* process the transaction on the datatree
* @param hdr the hdr of the transaction
* @param dt the datatree to apply transaction to
* @param sessions the sessions to be restored
* @param txn the transaction to be applied
*/
public void processTransaction(
TxnHeader hdr,
DataTree dt,
Map sessions,
Record txn) throws KeeperException.NoNodeException {
ProcessTxnResult rc;
switch (hdr.getType()) {
case OpCode.createSession:
sessions.put(hdr.getClientId(), ((CreateSessionTxn) txn).getTimeOut());
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(
LOG,
ZooTrace.SESSION_TRACE_MASK,
"playLog --- create session in log: 0x" + Long.toHexString(hdr.getClientId())
+ " with timeout: " + ((CreateSessionTxn) txn).getTimeOut());
}
// give dataTree a chance to sync its lastProcessedZxid
rc = dt.processTxn(hdr, txn);
break;
case OpCode.closeSession:
sessions.remove(hdr.getClientId());
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(
LOG,
ZooTrace.SESSION_TRACE_MASK,
"playLog --- close session in log: 0x" + Long.toHexString(hdr.getClientId()));
}
rc = dt.processTxn(hdr, txn);
break;
default:
rc = dt.processTxn(hdr, txn);
}
/*
* Snapshots are lazily created. So when a snapshot is in progress,
* there is a chance for later transactions to make into the
* snapshot. Then when the snapshot is restored, NONODE/NODEEXISTS
* errors could occur. It should be safe to ignore these.
*/
if (rc.err != Code.OK.intValue()) {
LOG.debug("Ignoring processTxn failure hdr: {}, error: {}, path: {}", hdr.getType(), rc.err, rc.path);
}
}
/**
* the last logged zxid on the transaction logs
* @return the last logged zxid
*/
public long getLastLoggedZxid() {
FileTxnLog txnLog = new FileTxnLog(dataDir);
return txnLog.getLastLoggedZxid();
}
/**
* save the datatree and the sessions into a snapshot
* @param dataTree the datatree to be serialized onto disk
* @param sessionsWithTimeouts the session timeouts to be
* serialized onto disk
* @param syncSnap sync the snapshot immediately after write
* @throws IOException
*/
public void save(
DataTree dataTree,
ConcurrentHashMap sessionsWithTimeouts,
boolean syncSnap) throws IOException {
long lastZxid = dataTree.lastProcessedZxid;
File snapshotFile = new File(snapDir, Util.makeSnapshotName(lastZxid));
LOG.info("Snapshotting: 0x{} to {}", Long.toHexString(lastZxid), snapshotFile);
try {
snapLog.serialize(dataTree, sessionsWithTimeouts, snapshotFile, syncSnap);
} catch (IOException e) {
if (snapshotFile.length() == 0) {
/* This may be caused by a full disk. In such a case, the server
* will get stuck in a loop where it tries to write a snapshot
* out to disk, and ends up creating an empty file instead.
* Doing so will eventually result in valid snapshots being
* removed during cleanup. */
if (snapshotFile.delete()) {
LOG.info("Deleted empty snapshot file: {}", snapshotFile.getAbsolutePath());
} else {
LOG.warn("Could not delete empty snapshot file: {}", snapshotFile.getAbsolutePath());
}
} else {
/* Something else went wrong when writing the snapshot out to
* disk. If this snapshot file is invalid, when restarting,
* ZooKeeper will skip it, and find the last known good snapshot
* instead. */
}
throw e;
}
}
/**
* truncate the transaction logs the zxid
* specified
* @param zxid the zxid to truncate the logs to
* @return true if able to truncate the log, false if not
* @throws IOException
*/
public boolean truncateLog(long zxid) {
try {
// close the existing txnLog and snapLog
close();
// truncate it
try (FileTxnLog truncLog = new FileTxnLog(dataDir)) {
boolean truncated = truncLog.truncate(zxid);
// re-open the txnLog and snapLog
// I'd rather just close/reopen this object itself, however that
// would have a big impact outside ZKDatabase as there are other
// objects holding a reference to this object.
txnLog = new FileTxnLog(dataDir);
snapLog = new FileSnap(snapDir);
return truncated;
}
} catch (IOException e) {
LOG.error("Unable to truncate Txn log", e);
return false;
}
}
/**
* the most recent snapshot in the snapshot
* directory
* @return the file that contains the most
* recent snapshot
* @throws IOException
*/
public File findMostRecentSnapshot() throws IOException {
FileSnap snaplog = new FileSnap(snapDir);
return snaplog.findMostRecentSnapshot();
}
/**
* the n most recent snapshots
* @param n the number of recent snapshots
* @return the list of n most recent snapshots, with
* the most recent in front
* @throws IOException
*/
public List findNRecentSnapshots(int n) throws IOException {
FileSnap snaplog = new FileSnap(snapDir);
return snaplog.findNRecentSnapshots(n);
}
/**
* the n recent valid snapshots
* @param n the number of recent valid snapshots
* @return the list of n recent valid snapshots, with
* the most recent in front
* @throws IOException
*/
public List findNValidSnapshots(int n) throws IOException {
FileSnap snaplog = new FileSnap(snapDir);
return snaplog.findNValidSnapshots(n);
}
/**
* get the snapshot logs which may contain transactions newer than the given zxid.
* This includes logs with starting zxid greater than given zxid, as well as the
* newest transaction log with starting zxid less than given zxid. The latter log
* file may contain transactions beyond given zxid.
* @param zxid the zxid that contains logs greater than
* zxid
* @return
*/
public File[] getSnapshotLogs(long zxid) {
return FileTxnLog.getLogFiles(dataDir.listFiles(), zxid);
}
/**
* append the request to the transaction logs
* @param si the request to be appended
* @return true iff something appended, otw false
* @throws IOException
*/
public boolean append(Request si) throws IOException {
return txnLog.append(si.getHdr(), si.getTxn(), si.getTxnDigest());
}
/**
* commit the transaction of logs
* @throws IOException
*/
public void commit() throws IOException {
txnLog.commit();
}
/**
*
* @return elapsed sync time of transaction log commit in milliseconds
*/
public long getTxnLogElapsedSyncTime() {
return txnLog.getTxnLogSyncElapsedTime();
}
/**
* roll the transaction logs
* @throws IOException
*/
public void rollLog() throws IOException {
txnLog.rollLog();
}
/**
* close the transaction log files
* @throws IOException
*/
public void close() throws IOException {
if (txnLog != null) {
txnLog.close();
txnLog = null;
}
if (snapLog != null) {
snapLog.close();
snapLog = null;
}
}
@SuppressWarnings("serial")
public static class DatadirException extends IOException {
public DatadirException(String msg) {
super(msg);
}
public DatadirException(String msg, Exception e) {
super(msg, e);
}
}
@SuppressWarnings("serial")
public static class LogDirContentCheckException extends DatadirException {
public LogDirContentCheckException(String msg) {
super(msg);
}
}
@SuppressWarnings("serial")
public static class SnapDirContentCheckException extends DatadirException {
public SnapDirContentCheckException(String msg) {
super(msg);
}
}
public void setTotalLogSize(long size) {
txnLog.setTotalLogSize(size);
}
public long getTotalLogSize() {
return txnLog.getTotalLogSize();
}
}
